Abstract

The present study aimed to assess the performance of sheep and goats finished in thinned Caatinga enriched with Cenchrus ciliares L. that
were given supplements. Twelve (12) Santa Inês sheep and 12 F1 crossbred goats (Boer x SRD) with live weight of 24.29 ± 1.35 kg were used in the
experiment. The experimental area was 2.4 ha, divided into four plots of 0.6 ha, two for each animal species. For assessment of the vegetation, each plot
was subdivided into 2 sub-plots of 0.3 ha. The animals were kept in pasture from 8:00 to 17:00 h, and then were brought into the stalls to receive energy
or protein-energy supplementation in an amount equivalent to 1.0% of the body weight. A completely randomized design was used with 2 x 2 factorial
arrangement (animal species x type of supplementation).

The finishing of sheep and goats in thinned Caatinga enriched with buffel grass was more favorable to the performance of goats compared to the consumption
of dry matter, organic matter, crude protein and neutral detergent fiber, with weights and carcass yields unchanged, though the lambs had better feed
conversion. Sheep and goats finished in thinned Caatinga enriched with buffel grass were more favored by protein-energy supplementation.

Keywords: carcass, dry matter intake, pasture, weight gain

Introduction

Most sheep and goats from Northeastern Brazil are raised on an extensive farming system, being mostly fed on native pasture of Caatinga, which is usually
improperly handled, exceeding its support capacity, resulting in low performance of the animals and causing significant environmental impact. However,
animal production can be considerably increased with the use of techniques for handling woody vegetation, as well as with dietary supplementation.

The control of woody species without forage value in the Caatinga, followed by the introduction of suitable grasses, has become a common practice among
producers, whose purpose is to increase the participation of the herbaceous layer in the production of edible dry matter. The Cenchrus ciliaris L.
is an exotic grass, resistant to drought and defoliation, which, depending on the physiological stage has protein levels of 3 to 15%. Also, it is one of
the species with potential for enrichment of Caatinga, increasing the production and quality of dry matter, improving the support capacity and the
performance of goats and lambs, whose meat is the main source of proteins for the population of the northeastern semiarid region. Yet, most producers still
have low production rates.

Santa Inês sheep and F1 Boer x SRD goats are characterized by their capacity for adaptation to the semiarid region, being resistant to diseases, and
represent an important source of income for farmers in the Northeast of Brazil. Quinzeiro Neto et al (2011) stressed that sheep has great potential for
meat production. Maia et al (2012) reported that, because of their higher growth rate and good carcass yield, Santa Inês sheep are becoming more popular
among producers compared to other woolless sheep.

Boer goats are characterize by: early growth, good conformation; good rates of fertility, fecundity, prolificacy and longevity; excellent maternal
qualities with adequate milk production and high rates of weaning (Marques et al 2013), being very suitable for crossing with SRD animals and native
breeds. The crossing of Boer goats with SRD animals produces offspring with higher growth rate (Freitas et al 2011). However, these animals do not
demonstrate their entire production potential because of their breeding system, particularly due to the decrease in the quality and quantity of dry matter
available throughout the year. Thus, the Caatinga vegetation becomes scarce, which requires an improved management, with the introduction of some sort of
supplementation.

Few studies use supplementation for goats and sheep under Caatinga conditions. On the other hand, there are doubts about the supplementation that should be
used, once the amount and quality of pasture the animals are put to graze may require different types of supplementation. Carvalho Júnior et al (2011)
reported that the use of concentrates in the diet of ruminants can increase the intake of energy and protein, and, thus, meet the demand of animals with
higher productivity.

Silva et al (2010) stressed that ruminants that graze in semiarid regions, including under Caatinga conditions (Leite 2002) usually require more energy
than protein. However, the actual need for supplementation will be determined by the botanical and chemical composition of the pasture and diet of the
animals, which is decisive to obtain animals with better performance and carcass yield compatible with the consumer market. Thus, the present study aimed
to assess the performance of sheep and goats finished in thinned Caatinga enriched with Cenchrus ciliaris L. cv. Biloela that were given two types
of supplementation.

Material and methods

Experimental area

The study was conducted at Farm Lameirão of Federal University of Campina Grande, located at the coordinates 7º1’ South latitude and 35º1’ West longitude.
According to Köppen’s classification, the region has a BShw climate – semiarid, with short rainy seasons in summer-autumn and rainfall mainly concentrated
in the months of March and April. The annual rainfall may vary from 150 to 1300 mm, but the highest average precipitation ever recorded is 500 mm. In 2010,
year in which the experiment was conducted, the monthly rainfall from January to December was respectively: 117.7; 31.8; 70.9; 188.2; 11.3; 61.5; 2.1; 0.0;
0.0; 70.9; 0.0 and 158.6 mm, totaling 713 mm: The dry period varies from six to eight months, beginning in June and ending in mid-January. The average
annual temperature is around 28 ºC, with maximum and minimum temperatures of approximately 35 and 22 ºC, respectively. The average relative humidity is
60%.

The woody vegetation of the experimental area was submitted to selective thinning to allow 15% of soil coverage (Araújo Filho 2013), which consisted in the
partial removal of undesirable species, preservation of species with high timber value and plants considered endangered and/or that stay green the year
round. For the control of thinned species, regrowths were cut during the rainy season. Caatinga was enriched with Cenchrus ciliaris L. cv. biloela
soon after thinning, with the seeds sown by scattering, and distributed as evenly as possible.

Animals and diets

The experiment was submitted to analysis and approved by the Research Ethics Committee of Universidade Federal de Campina Grande - Campus de Patos
(Protocol 29/2008).

Twelve (12) Santa Inês sheep and 12 crossbred goats with live weight of 24.29 ± 2.38 kg were used in the experiment. The animals were individually
identified with numbered collars. The experimental area was 2.4 ha, divided into four plots of 0.6 ha, two for each animal species, all of them with
shelter and water fountain. For assessment of the vegetation, each plot was divided into two subplots of 0.3 ha. During the experiment, the animals
received the routine treatments, such as vaccinations and endoparasite and ectoparasite control. The animals were randomized, with six animals per plot
(sheep or goats), corresponding go the continuous grazing stocking number of 0.54 UA/ha.

When the availability of DM of the herbaceous stratum surpassed 2000 kg/ha, or else, more than 50% of the potential of the thinned Caatinga (Araújo Filho
2013), two plots were occupied with sheep and two with goats. The diet was composed of native pasture enriched with Cenchrus ciliaris and
supplementation. The animals were kept in pasture from 8:00 to 17:00 h, and then were brought into the stalls to the energy supplement (ES) based on maize
meal (970 g/kg) or the protein-energy supplement (PES), consisting of soybean meal (500 g/kg) and ground maize grain (470 g/kg). Both supplements contained
30 g/kg of mineral premix for sheep (Santa Inês) or goat for the F1 Boer x SRD goats. The supplementation was provided in an amount equivalent to 10 g/kg
of the body weight that was weekly adjusted. (NRC 2007). The animals received water ad libitum in the field and in the stalls. The chemical
composition of the supplements is described in Table 1.

Table 1.
Chemical composition of the supplement provided to the sheep and goats

Component

Type of Supplementation

Energy Supplement

Protein-Energy Supplement

Dry Matter1

901

903

Mineral Matter2

16

38

Organic Matter2

984

962

Crude Protein2

118

269

Neutral Detergent Fiber2

235

244

Acid Detergent Fiber2

48

80

¹g/kg of NM (natural matter); 2g/kg of DM.

Sampling and chemical analyses

For estimating consumption, the combination of estimated fecal output, which was determined based on the external indicator hydroxyphenyl propane (LIPE ®) recommended by Rodríguez et al(2007) with the in vitro digestibility of the material collected in the rumen. After 30 days of the
experiment, the indicator was daily administered at a dosage of a 250 mg capsule directly into the rumen, through a tube, during 5 days. From the third day
of administration of the LIPE® samples of feces were manually collected directed from the rectal ampulla of the animals, homogenized to form
animal samples, which were pre-dried, milled and stored in bottles sent to the Department of Chemistry of Instituto de Ciências Exatas of UFMG for
estimates of fecal production.

The concentration of LIPE® was determined by red spectrometer (Rodríguez et al 2007). The estimated production of feces (FP) was obtained by the
equation: FP={(total LIPE administered/concentration of LIPE in the feces) x 100}.

The total collection in the rumen was made in two sheep and two goats with a ruminal fistula. On the day before collection, the animals were brought into
the stalls, fasted for 16 hours and then the total ruminal content was collected. The animals were allowed to graze for 20 minutes and then all the ruminal
material was collected and stored in polystyrene bottles with ice for further determination of dry matter (DM), crude protein (CP), neutral detergent fiber
(NDF), acid detergent fiber (ADF) and crude energy. For analysis of in vitro dry matter digestibility (IVDMD), 0.500 g of the sample were weighed in TNT
bags and then incubated in ANKOM 200 device (Ankon Technology Corp., Faiport, NY, USA), according to the methodology described by Silva and Queiroz (2002).

Slaughter and measurements

When the animals reached 35 kg of live weight or 75 days of experiment, they were fasted for 24 hours (solid) 16 hours (liquid), and weighed to obtain the
slaughter weight (SW). At slaughter, stunning and bleeding (both jugular veins and carotid arteries severed), followed by skinning and evisceration. The
gastrointestinal tract, bladder and gall bladder were removed, weighed and emptied to obtain the weights of the contents, and, thus, the empty body weight
(EBW), which was calculated by subtracting the weights of the contents from the SW.

The carcass was obtained after removal of the head and paws, and the hot carcass weight (HCW) was obtained. All components of the animal’s body not
included in the carcass weight were called “non-carcass components”, which were obtained by subtracting the HCW from the EBW. Among the non-components, the
weight and yield of liver, kidneys and gastrointestinal tract, tongue, esophagus, trachea and lungs, heart, head and paws were assessed. With HCW the
yields of the hot carcass (HCY) and biological yield (BY) were estimated, and then the carcasses were cooled at 4 ºC for 24 hours to obtain the cold
carcass weight (CCW) and the amount of carcass loss by cooling shrinkage (CS), with the methodology described by Cezar and Sousa (2007).

Statistical analyses

A completely randomized design was used with 2 x 2 factorial arrangement, with two animal species (sheep and goat) and two types of supplementation (energy
and protein-energy). The data were subjected to analysis of variance and the means were compared by Tukey test. The data were analyzed at 5% probability
level and processed by SAS (Statistical Analysis System, Version 9.1, 2003).

Results

Chemical composition, intake and digestibility

The chemical composition of the vegetation did not change in the areas where the sheep and goats grazed, reflecting the experimental planning adopted
(Table 2). Dicotyledons had a crude protein (CP) content of 106 g/kg, and dry matter (DM) content of 103 g/kg.

It is important to stress that the values of NDF of dicotyledons were 596 g/kg and 619 g/kg in the areas grazed by sheep and goats, respectively.

The DM content of Cenchrus ciliaris L. was lower in the May-July period than in the other periods, which can be associated to the phenological
cycle of the plant (Table 3). The highest DM content was observed in August, after the rainfall that lasted until July.

The CP content of Cenchrus ciliaris L., even in May 5, when DM content was 444 g/kg of NM (natural matter) was considered low (52 g/kg of DM). The
increase in CP content (65 g/kg) in July 5, em reflected the occurrence of rainfall, which made the regrowth of Cenchrus ciliaris L possible and,
thus, its selection by the animals.

Table 3.
Chemical composition of herbaceous vegetation in a thinned Caatinga enriched with Cenchrus ciliaris L. and grazed by sheep
and goats at different assessment times

There were no leftovers of the supplement offered to the animals, and the intake of concentrate (DM and OM) by the animals (10g of DM/kg of LW). The goats
consumed more DM and OM of bulk and total (g e g/kg of MW) than sheep (Table 4).

Regardless of the type of supplementation, the intake of DM and OM by the animals (Table 4) was similar, reflecting the high selective capacity of these
animals.

Table 4.
Dry matter and organic matter intake depending on the animal species and type of supplementation

The intake of CP of the concentrate did not differ between the species (Table 5). However, there was difference in the intake of CP (bulk and total), with
greater consumption of goats compared to sheep.

Regarding the type of supplementation, there was a difference in the consumption of CP of the concentrate and total.

Table 5.
Consumption (intake) of CP and NDF, depending on the animal species and type of supplementation

Variable

Animal species

p

Type of supplementation

p

SEM

Sheep

Goats

Energy

Protein-energy

Consumption of CP

Concentrate (g)

45

49

0.34

25

69

<.00

7.60

Bulk (g)

47

74

0.00

63

58

0.51

12.41

Total (g)

91

123

0.00

88

127

0.00

15.72

Consumption of NDF

Concentrate (g)

31

34

0.40

33

32

0.61

4.46

Bulk (g)

300

407

0.02

367

340

0.52

68.92

Total (g)

331

441

0.02

400

372

0.51

71.02

p = probability; SEM = standard error.

There was no difference between species for digestibility of DM, OM, CP and NDF (Table 6). However, regarding food conversion, the sheep showed 5.19
differing from the 6.02 obtained by the goats. Despite the greater consumption by goats, the performance of the animals did not differ.

Table 6.
Digestibility of DM, OM, CP and NDF depending on the animal species and type of supplementation

Digestibility (g/kg)

Animal species

p

Type of supplementation

p

SEM

Sheep

Goats

Energy

Protein-energy

Dry matter

637

640

0.85

642

635

0.71

0.03

Organic matter

666

674

0.63

676

664

0.49

0.03

Crude protein

614

659

0.05

561

712

0.001

0.04

Neutral detergent fiber

547

546

0.97

550

543

0.73

0.03

Food conversion

5.19

6.02

0.001

6.56

4.87

0.14

0.844

Initial weight (kg)

24.31

24.28

-

23.82

24.76

-

2.47

Total weight gain (kg)

8.12

8.57

0.53

7.50

9.18

0.02

1.75

Average daily weight gain (g)

130

140

0.43

120

150

0.05

0.03

p = probability; SEM = standard error.

As for supplementation, only digestibility of crude protein results differs, with a higher value for protein-energy supplementation.

The protein-energy supplementation supported a feed conversion of 4.87, while animals supplemented only with energy
had a conversion of 6.56.

Performance and carcass weight

As for performance, there was no difference between the species for total weight gain and average daily weight gain (Table 6). Regarding the types of
supplementation, the protein-energy supplementation provided greater total weight gain for the animals.

There was interaction between species and type of supplementation for the final weight (Table 7), with the sheep that received protein-energy
supplementation obtaining a higher final weight than the sheep that received energy supplementation.

On the other hand, the final weight of goats was similar in the two types of supplementation (Table 7).

Table 7.
Final weight (kg) of sheep and goats finished in thinned Caatinga enriched with Cenchrus ciliaris L. in each type of supplementation

Species

Type of supplementation

p

SEM

Energy

Protein-energy

Sheep

30.22

34.63

0.03

1.99

Goat

32.43

33.25

p = probability; SEM
= standard error.

There was no difference between the animal species for slaughter weight, amount of carcass loss by cooling shrinkage and biological yield. As for the
slaughter hot carcass, cold carcass and empty body weights of the animals that received protein-energy supplementation, they were greater than those
obtained by the animals given energy supplementation (Table 8), indicating the role of the protein of the concentrate in improving the low protein content
of the pasture.

Table 8.
Characteristics of the carcass of sheep and goats depending on the animal species and type of supplementation

Item

Animal species

p

Type of supplementation

p

SEM

Sheep

Goats

Energy

Protein-energy

Weights (kg)

Slaughter

30

30

0.51

29

31

0.00

1.67

Hot carcass

14

14

0.66

13

14

0.01

1.23

Cold carcass

13

13

0.53

13

14

0.01

1.11

Empty body weight

24

24

0.65

23

25

0.00

1.92

Yield (%)

Biological

58

58

0.96

59

58

0.42

1.90

Hot carcass

46

46

0.95

46

46

0.92

2.37

Cold carcass

45

45

0.77

45

45

0.74

2.27

Carcass loss by cooling shrinkage

4

3

0.15

4

3

0.36

1.32

p = probability; SEM
= standard error.

Discussion

Chemical composition, intake and digestibility

In the present study, dicotyledons had a crude protein (CP) content and dry matter (DM) content higher than the minimum dry matter (DM) content of 70 g/kg
for microbial growth in the rumen (Van Soest 1994).

The values of NDF of dicotyledons corroborating Formiga et al (2011) who reported that herbaceous dicotyledons tend to have lower NDF than grasses. This
aspect is stressed by the contribution of leguminous plants with high protein value among dicotyledons (Carvalho and Pires 2008).

The highest DM content was observed in August, after the rainfall that lasted until July, and which, according to Araújo Filho et al (2002) may induce or
hasten the physiological maturation of the plants, and, consequently, increase DM concentration.

The CP content of Cenchrus ciliaris L., even in May 5, when DM content was considered low, from a nutritional view, being lower than the minimum
70.0 g content needed for proper functioning of the rumen (Van Soest 1994).

In the present experiment, the goats consumed more DM and OM of bulk and total than sheep. The grazing habit of goats may have favored the higher intake of
bulk, since some herbaceous plants were in a more advanced phonological growth stage and with high altitude, which may difficult intake by sheep. (Osoro et
al 2013). The selective capacity of these animals was reported by Pereira Filho et al (2013) who stressed the high degree of use of the Caatinga vegetation
by sheep and goats, being considered intermediate selectors with high feeding flexibility, depending on the time of the year, availability and quality of
grazing.

The intake of CP (bulk and total), with greater consumption of goats compared to sheep. This finding can be associated to the ability of these animals to
select from among herbaceous plants, the broadleaf species, and, among these, the leguminous plants (Celaya et al 2007), which usually have greater protein
concentration than grasses, which are usually selected by sheep (Rutter 2006).

Regarding the type of supplementation, a difference in the consumption of CP of the concentrate and total is explained by the composition of supplements
with greater amount of CP in the case of protein-energy supplementation. In turn, the similar consumption of NDF in the two types of supplementation
reflects the animals’ capacity of selecting their diet, by adjusting the fibrous portion of the diet (Animut et al 2005).

The results for food conversion of sheep, which showed greater efficiency of feed conversion than goats, are consistent.

The results obtained in this paper for digestibility of MM for sheep and goats
was 630 g for sheep and 640 g for
goats, being consistent with the findings of Formiga et al (2011) who assessed
goats and sheep grazing in a Caatinga area enriched with buffel grass supplemented only with minerals, and obtained digestibility values for OM of 0.64 and
0.62 for sheep and goats, respectively. These results are considered satisfactory by the authors because they concern a native pasture at a dry season,
confirming the ability of sheep and goats of selecting diets of good nutritious value.

It is important to stress that the greatest intake of CP obtained with the protein-energy supplementation was not sufficient to establish a difference in
food conversion.

Performance and carcass weight

In a study with SRD goats, Voltolini et al (2009) found that energy supplementations had no effect on the average daily weight gain and total weight gain.

In a study with Santa Inês sheep finished on pasture that were given different levels of supplementation, Dantas et al (2008) obtained a daily gain of 148
g/day for sheep supplemented with 1% of LW. Carvalho Júnior et al (2011) assessing the performance of crossbred F1 (Boer x SRD) goats finished on native
pasture that were given different levels of supplementation obtained a gain of 147 g/day also with 1% of the LW in supplementation.

The result of the interaction between species and type of supplementation to the final weight, indicates that the protein concentration of the
protein-energy supplementation must have remedied the deficiency of the pasture, particularly if the CP values of Cenchrus ciliaris L and of the
native grasses are considered, which despite the high availability of DM, did not allow the sheep to select a diet that compensated the lower protein
intake in the energy concentrate.

Regarding the final weight of goats, the animals managed to supply their needs in the pasture, according to Formiga et al (2011), goats prefer shrubby,
broadleaf vegetable species, which have a higher CP content than grasses.

The results for carcasses of this study corroborate the findings of Silva et al (2010), who affirmed that animals in pastures in semiarid conditions need
more protein in their diet than the standard level of animals bred in temperate regions or in confinement.

Celaya R, Martínez A and Osoro K 2007 Vegetation dynamics in Cantabrian heath lands associated with improved pasture are as under single or mixed grazing
by sheep and goats. Small Ruminant Research, Volume 72, Article #2 Retrieved March 10, 2016.